As a companion to a recently funded contract (N01 CN-25434-01) for the chemoprevention of superficial transitional cell cancer (TCC) of the bladder, we propose to investigate intermediate molecular markers of TCC and their modulation by difluoro-methylornithine (DFMO), an irreversible inhibitor of the polyamine (PA) synthesizing enzyme, ornithine decarboxylase (ODC). In N01 CN-25434, 40 TCC and 20 non-TCC patients will have the biologic effects of 2 doses of DFMO (or placebo) determined in relevant targets (malignant and normal urothelial cells and tissues, and urine) to determine a biologically active DFMO dose to use in a placebo-controlled, Phase III, preventative trial in 240 patients with completely resected superficial TCC. The present investigation will utilize subjects in these studies to focus on interacting molecular pathways which are known to be altered in TCC and/or with ODC blockade/PA depletion. These include: 1) Pa metabolism; 2) the interaction of urinary epidermal growth factor (EGF) and its urothelial receptor (EGF-R) which is known to induce ODC activity in TCC cells; and 3) protein kinase C (PKC) which is an integral component of EGF signaling and ODC activation. Acetylated and unconjugated PA levels in urothelial tissues and urine (determined by HPLC) will be correlated with urothelial ODC activity (radiobioassay) expression (immunohistology) in patients with and without TCC and in those who are and are not receiving DFMO. Urinary [EGF] (RIA) and urothelial EGF-R expression (immunohistology/immunocytology) in these patients will be correlated with factors that influence (e.g. urinary pH), or result from (e.g. proliferation [Ki67 staining]) the EGF/EGF-R interaction, and with PA/ODC parameters. These will also be correlated with tissue profiles of predominant PKC isoforms (immunohistology) which are known to be differentially expressed in normal versus malignant cells in non-urothelial tissues. By comparing these parameters in patients with and without TCC, and particularly by repeating measurements in a longitudinal fashion in which disease outcome is being monitored, the effects of disease and its recurrence, as well as of ODC blockade will be better defined. These studies should provide important clinical information about molecular markers of malignant urothelial transformation, PA metabolism, and DFMO's biological effects as well as insights into the biology of TCC development, growth, and recurrence.